1. Field of the Invention
This invention relates generally to bending fixtures, and is concerned in particular with the provision of an improved method and apparatus for bending laying pipes for use in the laying heads of rod and bar rolling mills.
2. Description of the Prior Art
In one conventional laying pipe bending operation, an entire straight length of pipe is preheated and then manually bent and clamped along a single three dimensionally curved guide path. This operation requires a team of experienced mill personnel who must work quickly and in a carefully coordinated manner. In another conventional operation, the pipe is preheated, section by section, with each section again being manually bent and clamped along a single three dimensionally curved guide path. This operation requires considerable time, thereby limiting production to a few pipes per day. Moreover, both operations require mill personnel who must possess considerable skill and dexterity. The working conditions are relatively hazardous in that the mill personnel are intimately exposed to radiant heat from the heated pipe. Moreover, the results of the bending operation are likely to be unsatisfactory. For example, the pipe may not take on the precise three dimensional configuration being sought, or portions of the pipe may be cross-sectionally deformed.
Where such defects are pronounced and readily discernable, the pipe will be scrapped before being mounted for operation in a mill laying head. Here, the mill owner's loss is limited to the cost of the pipe and the unsuccessful bending operation. On the other hand, where the defects are not readily discernable, they may not be noticed until after the pipe is installed and running. Here, the mill owner's loss will be additionally compounded by ruined product and costly lost production time.